Follow footer preference guildance on some pages

- Footer preference should have a info icon in tethering page.
- Rmove an empty icon for screen attention setting.
- Revise the "More details" to "Learn more"
- Add more empty line between footer info and "Learn more"

Test: Built apk, and check the screen
Fix: 183472971
Fix: 183472858
Change-Id: I7edb71639b59efb8205c0ef6a50ab483f88aa63d